Comparison analysis of airline energy efficiency under weak disposability and strong disposability using a virtual frontier slack-based measure model

In this article, the energy efficiency of airlines has been studied with number of employees, capital stock, and tons of aviation kerosene as the inputs and revenue tonne kilometers, revenue passenger kilometers, total business income, and CO₂ emission as the outputs. Two new models, Virtual Frontier SBM (slack-based measure) with strong disposability and Virtual Frontier SBM with weak disposability, are proposed to calculate the energy efficiencies of 22 airlines from 2008 to 2012. We prove two important properties of Virtual Frontier SBM, which can show its advantages over traditional model. The main findings are (1) Scandinavian Airlines has the largest average energy efficiency in the period both in strong disposability and weak disposability; and (2) CO₂ emission has significant impacts on energy efficiency change in strong disposability, while it has little impact in weak disposability.